This paper proposes a computational method of contact forces working between multibody system and environment in forward dynamics based on both the microbody-deformation model and macro contact model. The combination of them simultaneously prevents the simulation from excess penetration in micro contact model and chattering in macro contact model. The difficulty lies on how to absorb the difference of duration between them. This problem is solved through the introduction of a timestep-dependent variable damper for a micro contact model and of error-norm minimization for a macro contact model